Newbie help with Astute 2022 ball diff, slipper clutch

[LewisA]

I've been trying to fine tune the slipper clutch however, after some wheelies the ball diff now feels Very gritty - oops.  Is barking the right description for the ball diff?

Setup is: 79/20x2.6= 10.27.  Motor is Tamiya Super Stock BZ 23T with gear ratio 9:1-11:1.  I'm struggling to get the ball diff and slipper to work well together without knackering the diff balls.

Should I just get new balls for the diff?  Or should i get a whole new ball diff kit?  Or ditch the ball diff and get a gear diff?

Thanks for any advice, Lewis

[Nick-W]

I can’t really help with the question of how to get them to work together, sorry. They were fine in mine (same motor as you) but I ended up getting a TA-06 gear diff anyway after a couple of runs because I wanted to keep tinkering. 

[Big Jon]

It sounds like you may have damaged some balls in the diffs, so go ahead and replace them. Once you’ve replaced the balls, go ahead and tighten the slipper until the spring is fully compressed, then break in the diff. Once it’s broken in, adjust the diff, tightening it until it doesn’t slip at all with full acceleration on a high traction surface. Once the diff is adjusted, loosen the slipper until it slips heavily under acceleration, then gradually tighten it until it slips for a couple of feet under acceleration, or you can use the “wheelie method”, where you hold the rear tires stationary, throttle the car, and set the slipper to slip when the front wheels are about an inch off the ground.

Breaking in ball diffs is something that’s commonly overlooked, and one of the (multiple) reasons ball diffs have gotten a bad rap. Tungsten balls last longer than ceramic ones, are more tolerant of slippage, and are easier on diff rings.

[stockae92]

On 4/2/2025 at 3:15 PM, Big Jon said:

It sounds like you may have damaged some balls in the diffs, so go ahead and replace them. Once you’ve replaced the balls, go ahead and tighten the slipper until the spring is fully compressed, then break in the diff. Once it’s broken in, adjust the diff, tightening it until it doesn’t slip at all with full acceleration on a high traction surface. Once the diff is adjusted, loosen the slipper until it slips heavily under acceleration, then gradually tighten it until it slips for a couple of feet under acceleration, or you can use the “wheelie method”, where you hold the rear tires stationary, throttle the car, and set the slipper to slip when the front wheels are about an inch off the ground.

Breaking in ball diffs is something that’s commonly overlooked, and one of the (multiple) reasons ball diffs have gotten a bad rap. Tungsten balls last longer than ceramic ones, are more tolerant of slippage, and are easier on diff rings.

thanks for the info. I need to do that before the first run for my TD2

[LewisA]

guys this is great, thank you

[Wooders28]

On 4/1/2025 at 9:21 PM, LewisA said:

I've been trying to fine tune the slipper clutch however, after some wheelies the ball diff now feels Very gritty - oops. 

Generally I start the other way around, start with the slipper too loose (but not slack.. ) and tighten rather than too tight and slacken.

Just remember there's a fair bit of heat generated in a slipper when it's slipping, so might want to do short bursts, and let it cool a bit, otherwise spurs get a bit melty (my DF03 spur....)🫣🤦‍♂️🤣

 

 

If its lifting the front end, it's too tight, in an ideal world you want the front end light, but not lifting, and slipping before the ball diff does. It's more about sight, feel and sound, rather than backing off the slipper xx turns etc.

 

On 4/1/2025 at 9:21 PM, LewisA said:

Should I just get new balls for the diff?

I would get aftermarket diff balls (I believe its Team Associated 3/32 balls for the TD2?) as the tamiya ones are usually just steel, and can roll out a bit like sausages, and loose the tension, where as the tungsten carbide balls in 'race cars' are much more harder wearing.

To build the diff, I follow Trish , the designer/ tech guy from Schumacher, if there's people that know about ball diffs, it's the company that invented them..

(Yeah its a Schumacher Laydown, but the procedure is pretty much the same)